A Comparative Study for Adsorptive Removal of Remazol Red R and Remazol Black B from Aqueous Solution by ZnO

Abstract

Adsorptive removal of remazol red R (RRR) and remazol black B (RBB) from aqueous solution has been investigated by
using ZnO as an adsorbent. Time for adsorption equilibrium, kinetics of adsorption at different initial concentrations of dyes
and adsorption isotherms at different temperatures have been studied. Adsorption capacity increased with increasing initial
dye concentration. The pseudo first-order and pseudo second-order kinetics were used to describe kinetic data and the rate
constants were evaluated. Experimental data fits better in the pseudo second-order kinetic model than in the pseudo firstorder
kinetic model for both the dyes. Langmuir and Freundlich isotherm models were applied to describe the adsorption of
RRR and RBB onto ZnO powders. Langmuir isotherm model provided a better correlation for the experimental data in
comparison to the Freundlich isotherm model. Adsorption of both RRR and RBB on ZnO are physical in nature and
increases with decreasing temperature. The equilibrium adsorption capacity decreases from 3.43 mg/g at 20 C to 2.36 mg/g
at 40 C for RRR whereas that in the case of RBB changes from 0.77 mg/g at 30 C to 0.75 mg/g at 40 C. Adsorption of
RRR on ZnO was found to be three times higher than the adsorption of RBB at a particular temperature. A model for
adsorption of both the dyes has been proposed.